Additive manufacturing method using microcapsule bonding and curing

Abstract

The invention discloses an additive manufacturing method using microcapsules for bonding and then curing. The additive manufacturing method comprises the following steps: S1, preparing microcapsules from powder needing to be formed, a binder and an auxiliary agent through a microcapsule production system; s2, replacing powder in a laser or electron beam powder sintering process with the microcapsule, and preparing a green body through a laser or electron beam powder sintering system; s3, the green body is taken out, and the binder is discharged; and S4, curing and molding the green body with the binder discharged into a required finished product. According to the additive manufacturing method using the microcapsules for bonding and then curing, an existing laser or electron beam powder sintering system can be used, powder in an existing laser or electron beam powder sintering process is replaced with the microcapsules, and then the microcapsules are cured; the defects of an existing laser or electron beam powder sintering process are overcome, so that a product with reusable materials and good product consistency is obtained, material waste is reduced, environmental harm is reduced, cost is reduced, and wide application of additive manufacturing is promoted.

Description

Technical Field

[0001] The present invention belongs to the technical field of additive manufacturing, and in particular relates to an additive manufacturing method using microcapsules bonded and then solidified. Background Art

[0002] At present, laser or electron beam powder sintering additive manufacturing usually uses powders developed specifically for the sintering process, and a high-power laser is used to heat the powder to the sintering temperature to form a solid. This process has some disadvantages, such as large dust and serious smoke pollution during the process, which affects the production environment, causes the equipment life to decrease, and the quality of the product will also be seriously affected.

[0003] At the same time, since the powder used is under long-term high temperature, its performance deteriorates quickly, and a large part of the powder in the laser sintering production process is actually discarded. This not only generates a lot of waste, but also greatly increases the cost.

[0004] In addition, the products currently produced by this process are usually unable to achieve batch consistency due to poor powder consistency, obvious thermal temperature gradients, smoke blocking the light path, etc., and have large tolerance errors, resulting in high manufacturing costs and unstable batch product quality.

[0005] Therefore, it is of great significance to develop an additive manufacturing method that can use the existing laser or electron beam powder sintering system to avoid the above-mentioned drawbacks of the existing process by improving the sintering powder into microcapsules and then solidifying it, so as to obtain reusable materials and products with good product consistency. Summary of the invention

[0006] Purpose of the invention: In order to overcome the above shortcomings, the purpose of the present invention is to provide an additive manufacturing method using microcapsules bonded and then solidified. The design is reasonable and the existing laser or electron beam powder sintering system can be used. By replacing the powder in the existing laser or electron beam powder sintering process with microcapsules and then solidifying, the disadvantages of the existing laser or electron beam powder sintering process are avoided, thereby obtaining reusable materials and products with good product consistency, reducing material waste, reducing environmental hazards, and significantly reducing costs, thereby promoting the widespread use of additive manufacturing.

[0007] The objective of the present invention is achieved through the following technical solutions: An additive manufacturing method using microcapsules bonded and then cured, comprising the following steps: S1 Preparation of microcapsules: Through the microcapsule production system, the powder to be formed is mixed with a binder and an additive, and granulated to obtain particles. The particles are wrapped with a layer of wall material through a wrapping device to form microcapsules; S2 green body forming: the above-mentioned microcapsules are used to replace the powder in the laser or electron beam powder sintering process, and a laser or electron beam powder sintering system is used to heat the microcapsules in the selected area with a low-power laser or electron beam. The microcapsules are melted by the heat and bonded together. After cooling into a solid layer, they are covered with another layer of microcapsules. The melting process is performed in the selected area according to the program, and the cycle is repeated until the green body is formed; S3: removing the green body and removing the binder; S4 solidification and molding: solidify and mold the green body from which the binder is discharged into the desired finished product.

[0008] The additive manufacturing method described in the present invention can use the existing laser or electron beam powder sintering system. By replacing the powder in the existing laser or electron beam powder sintering process with microcapsules, only a low-power laser or electron beam is needed to heat the microcapsules in the selected area. The microcapsules will stick together after being melted by the heat, and then be covered with a layer of microcapsules again after cooling into a solid layer. The melting procedure of the selected area is carried out according to the program, and the cycle is repeated until the green body is formed, which is then taken out and the binder is discharged using the method. Then, the green body after the binder is discharged is solidified and formed by a solidification molding method to form a final product.

[0009] Because of the wall protection, microcapsules are not easy to adsorb to each other, and the fluidity between the pellets is good. The green body can be taken out from the pellets by mechanical vibration, etc., which improves the automation efficiency of production. At the same time, the laser or electron beam power required in the production process is small, which makes it easy to achieve surface processing, and the microcapsules that are not heated are not affected and can be reused, which significantly reduces the cost.

[0010] Furthermore, in the above-mentioned additive manufacturing method using microcapsules bonded and then solidified, in S1, the material of the powder is one or a combination of non-metal and metal.

[0011] Furthermore, in the above-mentioned additive manufacturing method using microcapsules bonded and then solidified, the material of the powder includes plastic, rubber, ceramic, glass, synthetic fiber, composite material, copper, aluminum, iron, titanium, nickel, stainless steel and alloy.

[0012] Powder materials suitable for the method of the present invention include, but are not limited to, non-metals such as plastics, rubber, ceramics, glass, synthetic fibers and composite materials, and metals and alloys such as copper, aluminum, iron, titanium, nickel, stainless steel, etc. These materials are used in the present invention alone or in combination.

[0013] Furthermore, in the above-mentioned additive manufacturing method using microcapsules bonded and then cured, the binder is one or a combination of organic binders and inorganic binders.

[0014] Furthermore, in the above-mentioned additive manufacturing method using microcapsules for bonding and then curing, the binder includes paraffin, Fischer-Tropsch wax, polyethylene wax, polypropylene wax, acrylate, epoxy resin, polyurethane resin, polyamide, rubber, ethylene-vinyl acetate, polyvinyl alcohol, phenolic resin, urea-formaldehyde resin, phosphate, silicate, borate, copper salt, aluminum salt, sulfide, and silicone.

[0015] Binders suitable for the method of the present invention include, but are not limited to, paraffin wax, Fischer-Tropsch wax, polyethylene wax, polypropylene wax, acrylate, epoxy resin, polyurethane resin, polyamide, rubber, ethylene-vinyl acetate, polyvinyl alcohol, phenolic resin, urea-formaldehyde resin, phosphate, silicate, borate, copper salt, aluminum salt, sulfide, silicone and other organic and inorganic binders, which can be used alone or in combination in the present invention.

[0016] The binder, the powder to be formed and the auxiliary agent can be made into microcapsules that melt at a certain temperature. The capsule walls of the microcapsules have low adhesion to each other and have a certain strength, which can protect the powder mixture contained therein. The particles that are not melted by heat can be stable for a long time, can be repeatedly produced, and are easy to flow to realize automated production.

[0017] Furthermore, in the above-mentioned additive manufacturing method using microcapsules bonded and then cured, the auxiliary agent in S1 includes a foaming agent, a dispersant, an emulsifier, a stabilizer, and a plasticizer.

[0018] The auxiliary agents applicable to the method of the present invention include, but are not limited to, foaming agents, dispersants, emulsifiers, stabilizers, plasticizers, and crosslinking agents. These auxiliary agents can be applied to the present invention alone or in combination.

[0019] For example: adding a foaming agent to the microcapsule, the foaming effect is generated during curing, and the curing and foaming are formed in one piece. Dispersants help prevent the various components in the microcapsule raw materials from agglomerating during the mixing process, so that they are evenly dispersed in the system, thereby ensuring that the structure and performance of the microcapsules are uniform. When there are immiscible liquid phases in the system, emulsifiers can make them form a stable emulsion. During the preparation and storage of microcapsules, stabilizers can prevent microcapsules from agglomerating, settling or decomposing, and improve the stability and service life of microcapsules. Plasticizers can increase the flexibility and plasticity of microcapsule wall materials, making them easier to process and shape, and can also improve the mechanical properties of microcapsules.

[0020] Furthermore, in the above-mentioned additive manufacturing method using microcapsules bonded and then solidified, in S1, the wall material is one or a combination of multiple of polysaccharides, proteins, celluloses, starch derivatives, polyesters, polyurethanes, polyacrylates, fatty acids, polyvinyl alcohol, calcium carbonate derivatives, and calcium phosphate derivatives.

[0021] Furthermore, in the above-mentioned additive manufacturing method using microcapsules bonded and then solidified, the S2 specifically includes the following contents: replacing the powder in the laser or electron beam powder sintering process with the microcapsules obtained in S1, and using a laser or electron beam powder sintering system to heat the microcapsules in the selected area with a low-power laser or electron beam, that is, the laser generator emits laser light to the scanning galvanometer and the surface laser mirror, and the light path is allocated to the area set by the program to heat the microcapsules in the forming cylinder, or the electron gun generates an electron beam and scans and heats the microcapsules in the forming cylinder in the selected area through an electron lens; after the microcapsules are melted by heat, the microcapsules are melted and bonded together to form a controlled bonding layer, and after cooling into a solid layer, the microcapsules in the feeding cylinder are fed into the forming cylinder by a roller or a scraper, and the cycle is repeated and superimposed until the green body is formed.

[0022] Preferably, the process of bonding the microcapsules after melting under heat in S2 can also be replaced by direct laser sintering or electron beam sintering after heating. In this case, the wall material of the microcapsules is reinforced with organic fibers or inorganic fibers to prevent the heat from expanding in the heated area, thereby ensuring the integrity of the microcapsule particles in the non-heated area.

[0023] The above design can reduce the defects of material aging, smoke generation and unstable quality generated in the current sintering process.

[0024] Furthermore, in the above-mentioned additive manufacturing method using microcapsules for bonding and then curing, the method of discharging the binder in S3 includes using a solvent and changing the temperature.

[0025] The S2 embryo is taken out and the binder is expelled by using solvents, temperature changes, etc.

[0026] Furthermore, in the above-mentioned additive manufacturing method using microcapsules bonded and then cured, the curing and molding method in S4 includes moisture curing, light curing, radiation cross-linking, microwave curing, vacuum curing, thermal curing, chemical curing, biological curing, and sintering.

[0027] Compared with the prior art, the present invention has the following beneficial effects: (1) The additive manufacturing method using microcapsules for bonding and curing disclosed in the present invention replaces the powder in the existing laser or electron beam powder sintering process with microcapsules, and changes the laser or electron beam powder sintering process to a binder fluid formed after the microcapsules are heated and melted to bond the powders to be formed together. The laser or electron beam power required in the molding process is small, and surface processing is easy to achieve. In addition, the microcapsules that are not heated are not affected and can be reused, which significantly reduces the cost. In addition, the microcapsules are not easily adsorbed to each other because they are protected by walls, and the fluidity between the pellets is good, which makes it easy to remove the green body from the pellets, thereby improving the efficiency of automated production. (2) The additive manufacturing method using microcapsule bonding and post-curing disclosed in the present invention can use the existing microcapsule production system, laser or electron beam powder sintering system and mature curing process, with low investment, and can be directly applied to most existing material varieties, thereby reducing material waste, reducing environmental hazards, significantly reducing costs, and improving product performance, thereby promoting the widespread use of additive manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic diagram of microcapsule production in the additive manufacturing method using microcapsules bonded and then cured according to the present invention; Figure 2 A schematic diagram of the microcapsule structure of the additive manufacturing method using microcapsules bonded and then cured according to the present invention; Figure 3 It is a production schematic diagram of S2 of the additive manufacturing method using microcapsules bonded and then cured according to the present invention; Figure 4 It is a production schematic diagram of S3 of the additive manufacturing method using microcapsules bonded and then cured according to the present invention; Figure 5 Schematic diagram of the production of S4 of the additive manufacturing method using microcapsules bonded and then cured according to the present invention.

[0029] In the figure: microcapsule 1, encapsulation equipment 2, particles 3, wall material 4, laser generator 5, scanning galvanometer and surface laser mirror 6, roller or scraper 7, bonding layer 8, adhesive 9, green body 10, finished product 11. DETAILED DESCRIPTION

[0030] The following will be attached Figure 1-5 Embodiments The technical solutions in the embodiments of the present invention are clearly and completely described in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention. The following example provides an additive manufacturing method using microcapsule bonding followed by curing. Example

[0031] like Figure 1-5 As shown, this embodiment uses an additive manufacturing method in which microcapsules are bonded and then cured, and includes the following steps: S1: Preparation of microcapsules.

[0032] like Figure 1As shown, through the existing microcapsule production system, the powder to be formed is mixed with a binder and an auxiliary agent, and granulated to obtain particles 3. The particles 3 are wrapped with a layer of wall material 4 through a wrapping device 2 using the existing microcapsule wrapping technology to form microcapsules 1.

[0033] like Figure 2 As shown, the structure of the microcapsule 1 is as follows: the inner core is a particle 3 formed by mixing powder to be molded with a binder and an auxiliary agent, and the outer core is wrapped with a layer of wall material 4 that can be used for reinforcement.

[0034] Among them, the powder materials applicable to the present embodiment include but are not limited to: non-metals such as plastics, rubber, ceramics, glass, synthetic fibers and composite materials, as well as metals and alloys such as copper, aluminum, iron and titanium, nickel, stainless steel, etc., which are applied to the present invention alone or in combination. The binders applicable to the present embodiment include but are not limited to: paraffin, Fischer-Tropsch wax, polyethylene wax, polypropylene wax, acrylate, epoxy resin, polyurethane resin, polyamide, rubber, ethylene-vinyl acetate, polyvinyl alcohol, phenolic resin, urea-formaldehyde resin, phosphate, silicate, borate, copper salt, aluminum salt, sulfide, organic silicon and other organic and inorganic binders, which are applied to the present invention alone or in combination. The auxiliary agents applicable to the present embodiment include but are not limited to: foaming agent, dispersant, emulsifier, stabilizer, plasticizer, cross-linking agent, which are applied to the present invention alone or in combination. The wall materials 4 applicable to the present embodiment include but are not limited to: polysaccharides, proteins, cellulose, starch derivatives, polyesters, polyurethanes, polyacrylates, fatty acids, polyvinyl alcohol, calcium carbonate derivatives, calcium phosphate derivatives.

[0035] S2: Green forming.

[0036] The microcapsules 1 prepared by S1 replace the powder in the laser or electron beam powder sintering process, and the microcapsules 1 in the selected area are heated by a laser or electron beam powder sintering system using a low-power laser or electron beam. The microcapsules 1 are melted by heat and bonded together, and then covered with a layer of microcapsules 1 again after cooling into a solid layer. The melting process is performed in the selected area according to the program, and the cycle is repeated until the green body is formed. Different from the existing removal method and powder cleaning process (which requires a lot of manual labor), the unmelted microcapsules 1 in this embodiment have low adhesion and can flow out by mechanical means such as vibration, thereby improving the level of automation.

[0037] like Figure 3 As shown, the laser generator 5 emits laser light to the scanning galvanometer and the surface laser mirror 6, and the optical path is allocated to the area set by the program to heat the microcapsules 1 in the forming cylinder. After the capsule wall of the microcapsule 1 is heated and melted, the binder particles in the inner core and other heated and melted particles are bonded to each other to form a controlled bonding layer 8. The microcapsules 1 in the feeding cylinder are fed into the forming cylinder by a roller or a scraper 7, and the green body 10 is formed by repeated cycles of stacking.

[0038] Alternatively, the electron beam generated by the electron gun is scanned and heated through the electron lens to heat the microcapsules 1 in the selected area of ​​the forming cylinder. The microcapsules 1 are melted by the heat and bonded together to form a controlled bonding layer 8. After cooling into a solid layer, the microcapsules 1 in the feeding cylinder are fed into the forming cylinder by a roller or a scraper 7, and the cycle is repeated and superimposed until the green body 10 is formed.

[0039] Alternatively, the microcapsule 1 is directly laser sintered or electron beam sintered after being heated. In this case, the wall material 4 of the microcapsule 1 is reinforced with organic fiber or inorganic fiber, which can prevent the heat from expanding in the heated area, thereby ensuring the integrity of the microcapsule 1 particles in the non-heated area. This can reduce the defects of material aging, smoke, and unstable quality that occur in the current sintering process.

[0040] S3: Discharge the binder like Figure 4 As shown, the green body 10 in S2 is taken out, and the green body 10 can discharge the binder 9 by temperature change and solvent dissolution.

[0041] S4: Curing and molding.

[0042] like Figure 5 As shown, the green body from which the binder is discharged in S3 is formed into the desired finished product 11 by moisture curing, light curing, radiation cross-linking, microwave curing, vacuum curing, chemical curing, thermal curing, electron beam curing, biological curing, sintering, etc.

[0043] In summary: This embodiment provides an effective additive manufacturing method using microcapsules bonded and then cured, which can directly use existing common raw materials, and form microcapsules through mature granulation and microcapsule encapsulation technology, and use existing laser or electron beam powder sintering equipment and processes, and existing powder injection molding process debinding equipment to remove the binder, and then use a widely used curing system to finally complete the finished product, avoiding the shortcomings of existing additive manufacturing such as high material loss and large product deformation, with controllable quality and high reproducibility, and is suitable for large-scale automated production.

[0044] The present invention has many specific application paths, and the above is only a preferred embodiment of the present invention. It should be pointed out that the above embodiments are only used to illustrate the present invention, and are not used to limit the protection scope of the present invention. For those of ordinary skill in the art, several improvements can be made without departing from the principle of the present invention, and these improvements should also be regarded as the protection scope of the present invention.

Claims

1. An additive manufacturing method using microcapsules bonded and then cured, characterized in that: The steps include: S1 Preparation of microcapsules: Through the microcapsule production system, the powder to be formed is mixed with a binder and an additive, and granulated to obtain particles. The particles are wrapped with a layer of wall material through a wrapping device to form microcapsules; S2 green body forming: the above-mentioned microcapsules are used to replace the powder in the laser or electron beam powder sintering process, and a laser or electron beam powder sintering system is used to heat the microcapsules in the selected area with a low-power laser or electron beam. The microcapsules are melted by the heat and bonded together. After cooling into a solid layer, they are covered with another layer of microcapsules. The melting process is performed in the selected area according to the program, and the cycle is repeated until the green body is formed; S3: removing the green body and removing the binder; S4 solidification and molding: solidify and mold the green body from which the binder is discharged into the desired finished product.

2. The additive manufacturing method using microcapsules bonded and then cured according to claim 1, characterized in that: In S1, the material of the powder is one or a combination of non-metal and metal.

3. The additive manufacturing method using microcapsules bonded and then cured according to claim 2, characterized in that: The material of the powder is one or a combination of plastic, rubber, ceramic, glass, synthetic fiber, composite material, copper, aluminum, iron, titanium, nickel, stainless steel and alloy.

4. The additive manufacturing method using microcapsules bonded and then cured according to claim 1, characterized in that: In the above S1, the binder is an organic binder, an inorganic binder or a combination of more than one thereof.

5. The additive manufacturing method using microcapsules bonded and then cured according to claim 4, characterized in that: The binder is one or a combination of paraffin wax, Fischer-Tropsch wax, polyethylene wax, polypropylene wax, acrylate, epoxy resin, polyurethane resin, polyamide, rubber, ethylene-vinyl acetate, polyvinyl alcohol, phenolic resin, urea-formaldehyde resin, phosphate, silicate, borate, copper salt, aluminum salt, sulfide, and silicone.

6. The additive manufacturing method using microcapsules bonded and then cured according to claim 1, characterized in that: In S1, the auxiliary agent is one or a combination of multiple agents selected from the group consisting of a foaming agent, a dispersant, an emulsifier, a stabilizer, and a plasticizer.

7. The additive manufacturing method using microcapsules bonded and then cured according to claim 1, characterized in that: In S1, the wall material is one or a combination of polysaccharides, proteins, celluloses, starch derivatives, polyesters, polyurethanes, polyacrylates, fatty acids, polyvinyl alcohol, calcium carbonate derivatives, and calcium phosphate derivatives.

8. The additive manufacturing method using microcapsules bonded and then cured according to claim 1, characterized in that: The S2 specifically includes the following contents: replacing the powder in the laser or electron beam powder sintering process with the microcapsules prepared in S1, and using a laser or electron beam powder sintering system to heat the microcapsules in the selected area with a low-power laser or electron beam, that is, the laser generator emits laser light to the scanning galvanometer and the surface laser mirror, and the light path is distributed to the area set by the program to heat the microcapsules in the forming cylinder, or the electron gun generates an electron beam and scans and heats the microcapsules in the forming cylinder in the selected area through an electron lens; the microcapsules are melted by heat and bonded together to form a controlled bonding layer, and after cooling into a solid layer, the microcapsules in the feeding cylinder are fed into the forming cylinder by a roller or a scraper, and the cycle is repeated and superimposed until the green body is formed.

9. The additive manufacturing method using microcapsules bonded and then cured according to claim 1, characterized in that: The method of discharging the binder in S3 includes using a solvent and changing the temperature.

10. The additive manufacturing method using microcapsules bonded and then cured according to claim 1, characterized in that: The curing and molding methods in S4 include moisture curing, light curing, radiation cross-linking, microwave curing, vacuum curing, thermal curing, chemical curing, biological curing, and sintering.

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